JPH08311319A - Resin composition for electric insulation and enameled wire - Google Patents

Abstract

PURPOSE: To obtain the subject composition suffering no deterioration of is properties even when baked at a higher rate than the previous to make an enameled wire, comprising a polyester resin produced by using a specific amount of a titanium alcoholate ass esterification catalyst. CONSTITUTION: This composition comprises a polyester resin obtained by reacting (A) a polyhydric alkcohol component with (B) a polybasic acid component by use of, as an esterfication catalyst, 0.5wt.% or more, preferably 2 to 3wt.% based on the total amount of the components A and B, of an alcohlate of titanium (e.g. tetrabutyl titanate). It is preferable to use triol(s) such as glycerol in a proportional amount of 40 to 60(equivalent)% based on the components A. As the component B, it is recommended to use terephthalic acid or an alkyl terephthalate in a proportional amount of 40 to 100% based on the component B. In addition, in order to improve the heat resistance of the composition, it is preferable to combinedly use an imidic acid of the formula (R1 is a trivalent organic group; R2 is a divalent organic group) in a proportional amount of 5 to 40% based on the component B. In addition, it is recommended to use the component A and B so that the equivalent ratio of the OH group to carboxyl group is 1.4 to 1.8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrical insulating resin composition and an enamel wire.

[0002]

2. Description of the Related Art Conventionally, polyester varnish is often used as a resin composition for electrical insulation, particularly a resin composition for enameled wire, because it has a relatively good balance of mechanical properties, electrical properties and heat resistance. There is. However, from the viewpoint of streamlining the manufacturing process and improving productivity of enameled wire manufacturers in recent years, there has been a demand for a polyester varnish having a high-speed baking property and having no property deterioration. The properties of conventional polyester varnish are remarkably inferior when baked at an appropriate baking speed or higher. The main reason for this is that the curing speed of the polyester varnish is slow, and when baked at an appropriate baking speed or higher, the polyester resin does not have a sufficiently high molecular weight and the coating film does not exhibit sufficient toughness and heat resistance. . Therefore, in order to further increase the baking speed, it is necessary to improve the hardening speed of the polyester varnish.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and a resin composition for electrical insulation in which the characteristics are not deteriorated even when a conductor is baked to form an enamel wire at a higher speed than before. An enamel wire using this is provided.

[0004]

A resin composition for electrical insulation according to the present invention comprises a polyhydric alcohol component and a polybasic acid component which are esterified with 0.5% by weight or more of a titanium alcoholate based on the total amount of these components. It contains a polyester resin obtained by reacting by using as a catalyst.

Examples of the titanium alcoholate used in the present invention include lower alcohol alcoholates such as tetrabutyl titanate and tetraisopropyl titanate. When the amount of the catalyst is less than 0.5% by weight based on the total amount of the polybasic acid component and the polyhydric alcohol component, the effect of improving the characteristics during high speed baking tends to be small. The amount of the catalyst is preferably 2 to 3% by weight based on the above total amount. If the amount of catalyst is too large, the flexibility tends to decrease.

Examples of the polyhydric alcohol component include diols such as ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol and 1,6-hexanediol,
Triols such as glycerin, tris-2-hydroxyethyl isocyanurate, trimethylolpropane, and hexanetriol are used, but the triol is preferably in the range of 30 to 80 equivalent% of the polyhydric alcohol component, and more preferably Is in the range of 40 to 60 equivalent%. If the blending ratio of triols is small, the curability and heat resistance may be poor, and if it is too large, the adhesion and flexibility may be poor.

As the polybasic acid component, terephthalic acid or alkyl terephthalate is used as an essential component. Although terephthalic acid itself may be used, an alkyl terephthalate obtained by a transesterification reaction, such as dimethyl terephthalate, monomethyl terephthalate, and diethyl terephthalate may be used. The amount of terephthalic acid or alkyl terephthalate used is 4 with respect to the polybasic acid component.
The range of 0 to 100 equivalent% is preferable. In order to improve heat resistance, the general formula (1)

Embedded image (In the formula, R ₁ represents a trivalent organic group and R ₂ represents a divalent organic group) is preferably used in combination.
Examples of the imide acid include imide dicarboxylic acid obtained by reacting 2 mol of trimellitic anhydride with 1 mol of diamine (see Japanese Patent Publication No. 51-40113). The diamine and trimellitic anhydride may be added at the time of producing the hydroxyl group-containing polyester without being converted to imidodicarboxylic acid in advance. As diamine, 4,4'-diaminodiphenylmethane, 4,4'-
Examples include diaminodiphenyl ether.

The amount of imide acid used is 3 to 6 of the polybasic acid component.
The range of 0 equivalent% is preferable, and the range of 5 to 40 equivalent% is more preferable. If the amount of imidic acid used is too small, the heat resistance tends to be poor, and if it is too large, the appearance of the enameled wire may deteriorate.

As the polybasic acid component, for example, isophthalic acid, which is commonly used in polyester varnish for enamel copper wire,
You may use together adipic acid, sebacic acid, etc.

The mixing ratio of the polyhydric alcohol component and the polybasic acid component is not particularly limited, but from the viewpoint of flexibility and heat resistance, the equivalent ratio of hydroxyl group to carboxyl group is 1.2 to.
It is preferably 2.4, and more preferably 1.4 to 1.8.

If necessary, a curing agent such as tetrabutyl titanate may be added to the resin composition for electrical insulation of the present invention, and a metal salt such as zinc, lead or manganese of an aromatic carboxylic acid may be added to the exterior. You may add as a improver. Further, since the viscosity at the time of synthesis is high, it is preferable to perform the synthesis in the coexistence of a cresol-based solvent such as phenol, cresol, or xylenol.

The resin composition for electrical insulation of the present invention is applied to a conductor such as a copper wire and baked to give an enameled wire excellent in various properties such as flexibility and heat resistance. Since it has excellent curability, the enamelled wire characteristics do not deteriorate even when baked at a higher speed than in the past.

[0013]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In the examples,% means% by weight unless otherwise specified.

Example 1 39.6 g of 4,4'-diaminodiphenylmethane was placed in a four-necked flask equipped with a thermometer, a stirrer and a condenser.
(0.4 equivalent), 76.8 g of trimellitic anhydride (0.
8 equivalents), 349.2 g of dimethyl terephthalate (3.6
Equivalent), glycerin 73.0 g (2.38 equivalent), ethylene glycol 99.8 g (3.22 equivalent), cresol 114 g and esterification catalyst 12.8 g (tetrabutyl titanate) were added, and the mixture was heated to 170 ° C. in a nitrogen stream. The temperature was raised and the reaction was carried out for 3 hours. The resulting solution is then 215
The temperature was raised to ° C and the reaction was carried out for 6 hours to synthesize polyester.
To the obtained resin solution, 583 g of cresol was added, and 26.4 g of tetrabutoxytitanate and 25.3 g of zinc naphthenate (metal content 6%) were added to obtain a polyester resin liquid having a nonvolatile content of 40%.

Example 2 Example 1 was repeated except that the amount of tetrabutyl titanate used was 3.2 g (0.5% by weight).

Comparative Examples 1 and 2 39.6 g of 4,4'-diaminodiphenylmethane were placed in a four-necked flask equipped with a thermometer, a stirrer and a condenser.
(0.4 equivalent), 76.8 g of trimellitic anhydride (0.
8 equivalents), 349.2 g of dimethyl terephthalate (3.6
Equivalent), glycerin 73.0 g (2.38 equivalent), ethylene glycol 99.8 g (3.22 equivalent), cresol 114 g and esterification catalyst 0.64 g (Comparative Example 1).
Was charged with tetrabutyl titanate, and Comparative Example 2 was lead acetate), and the temperature was raised to 170 ° C. in a nitrogen stream and reacted for 3 hours. Next, the obtained solution was heated to 215 ° C. and reacted for 6 hours to synthesize polyester. 583 g of cresol was added to the obtained resin solution, and 26.4 g of tetrabutoxy titanate and zinc naphthenate (metal content 6%) 25.
3 g was added to obtain a polyester resin liquid having a nonvolatile content of 40%.

The resin compositions obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were applied to a copper wire having a diameter of 1.0 mm according to the following baking conditions.
In Comparative Examples 1 and 2, baking was performed at linear velocities of 15 m / min and 17 m / min to produce an enamel wire. [Baking conditions] Baking furnace: Hot-air type vertical furnace (furnace length 5.5 m) Furnace temperature: Inlet / outlet = 320 ° C / 430 ° C Coating method: Dice 6 times
The results are shown in Table 1.

[0018]

[Table 1]

[0019]

According to the electrical insulating resin composition of the present invention, it is possible to produce an enamel wire having excellent properties such as crazing resistance and heat resistance even when it is baked at a much higher speed than before. It is very useful industrially. The enameled wire according to claim 2 is obtained by baking at a high speed, and is excellent in various properties such as crazing resistance and heat resistance.

Claims (2)

[Claims] 1. A polyhydric alcohol component and a polybasic acid component,
A resin composition for electrical insulation comprising a polyester resin obtained by reacting 0.5% by weight or more of titanium alcoholate as an esterification catalyst with respect to the total amount of these. 2. An enameled wire obtained by applying the resin composition for electrical insulation according to claim 1 onto a conductor and baking it.